>>The methodology is not about testing the efficiency of
>the
>>whole AF system in real life situations. It is about
>testing
>>wether or not, on the simplest possible target, phase
>>detection produces front or back focusing.
>
>I understand your approach. What I'm suggesting is that I
>believe the simplification is largely counterproductive
>because I think it inherently prevents the chosen sensor
>(which is part of a larger system) from functioning most
>effectively (as a fundamental part of the larger system) for
>the application dictated by your methodology. Some AF system
>experts should chime in here I think.
>
>>If the camera is not successful at properly focusing such
>a
>>target, it's a clear sign there is a problem. You cannot
>hope
>>to get good results in real life situations like you
>describe
>>if the camera cannot even handle ideal conditions. It's
>just
>>step zero in the troubleshooting strategy.
>
>My point is that the condition you set up in your methodology
>is not in fact ideal. I believe that isolating a target to
>provide, effectively, a single data registration point for the
>AF system, does not reflect the engineering or software design
>approach of the AF system. The AF system is designed to work
>best, as I understand it, when provided with significantly
>more target and proximal data than is provided when using your
>method.

This is only true in the multi-point AF modes. In single-servo, single-point AF the only data that is important is that which is under the selected focus point. If the camera can not perform well in this mode on a target with good contrast (in the proper plane), there is no reason to believe it would perform well in "real-world" situations.

While the camera may achieve better results on still subjects using single-servo, dynamic-area or continuous-servo, dynamc-area or 3D-tracking when the single-servo, single-point results are poor, this is completely beside the point.

If all of the focus points did work well in single-servo, single-point, I would bet a lot of money that the performance in continous-servo and dynamic-area modes would improve greatly.

IMO it's a ignoratio elenchi to say "yes AF-S single-point doesn't work well in test scenarios, use AF-C dynamic-area in the real-world."

--
RL

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